Home Forums Gear Hunting Trucks and Four-Wheel Drives 6.7 cummins how are they?

looking at one and need yalls input.

I have one in my 04 3500 4x4 and love it. The only thing I have done to the truck is put a 5" straight exhaust. This truck will flat out haul some a$$. Ive had mine since 05 and put about 60000 miles on it and then only trouble I have had is the fuel pump went out. That was an easy $175 fix. I say get one and don't look back. I'm already looking for another one.

coyoteman23

I was looking and bought at the end of the summer in 08. I passed on the 08 models and bought an 07 that had the 5.9 CTD. The early 08 6.7 had a lot of problems with the pollution BS according to a lot of owners and the mechanics at the dealership. I have heard that the 09 6.7 has most of the problems resolved. Do a search of 6.7 problems and you will see some of the issues. Good Luck.

I am not sure what Coyoteman23, a 6.7 in a 2004?

The 6.7 was first made available in the 07.5 model. Yes, that first run seemed to have a lot of issues with the emissions system. Clogged DPF's, turbos sooted up, EGR issues, etc. I bought an 08 and couldn't be happier. I traded in my 06 5.9L, which was a great truck. I loved that truck........ and the new 08 blows that one away! Much nicer truck, big time power upgrade in my opinion, stock 08 vs. stock 06. Overall, it is the same truck, but the 6.7L and the 6spd auto put it far ahead of the 5.9L and 4spd auto. The 4spd auto was pure slop, terrible trans I thought. Then you also have the e-brake which is standard with the 6.7L. It is my first e-brake and I love it. I am only at 10k miles, but love the truck, and not a single problem yet. I might think twice about buying the 07.5, but would do another 08 without hesitation.

Brent

Forgot to mention the downside....MPG is not quite up to snuff as the 5.9L. My 06 would do 16/20. The 08 is closer to 14/17. Still pretty decent mileage for all the power it puts out. Some have deleted the entire emissions system for improved mileage, but not willing to void my warranty for the increase in MPG. If you really want some info on the new Cummins, check out Cumminsforum.com.

The 6.7's had issues with the particulate filter and the regeneration process not working correctly. After several flashes, I can say that the probelm is 99% resolved. The one thing we keep ruinning into with these engines is idle time. People are idling these trucks for hours and hours and the regeneration process will not happen at idle and truck not moving. I think it has to do with the exhaust getting up to 1300 degrees to clean out the filter. Anyways, if you pull you will love the power and the built in exhaust brake.
The 6.7 don't have any of the problems the 5.9 (610 torque) have with injectors. The only real issue has been the particulate filter which seems to be all but gone.

Hemi

Decent advice posted above. www.dieseltruckresouce.com has a forum for 6.7 engines. Once the initial problems were solved with the 07.6s and 08s people have been happy with their trucks. The only issue is mileage, down substantially from the 5.9 in spite of the new transmission. Lots of people are installing dfp delete kits and getting increases in power and mileage.

Got a buddy that bought an 08 from Dave Smith in Idaho and drove it back up to Alaska. Only problems he's been having is the idle time required to keep a diesel running up here in the constant sub zero weather affecting the EPA bullchit. And the fuel mileage isn't what he expected after hearing a lot of us that had 5.9's talk. My 01 5.9L w/ the 6spd got about 17 in town and 21+ on the highway, he's getting about 13 in town and 17 on the highway, buts its been reading far less than that all winter with all the idle time as you could imagine. Diesel is about $3.50 a gallon up here where he lives, so he's not too happy about the fuel mileage mostly.

Have your pal check some of the Cummins sites.....folks are getting good milege increases simply by unplugging the EGR valve .


I'll own a 6.7 eventually , with the 6 speed auto . And it'll have the EGR and DFP crap thrown in the crick......

Hemi:

What is the nature of the injector problems that plague the 5.9l? We are looking at several used ones and are trying to get a handle on any common 5.9 issues.

Thanks,
Logger

You are correct Brent. Mine has the 5.9. I just saw Cummins and got all excited I guess. LOL I do however love my 5.9. Its gets great MPG and has loads of torque.

coyoteman23

I meant to post a pic of in my last post and forgot. Here it is. The truck is shown with the factory 265 tires. Now I am running 285's for a lil more height. I like the bigger tires better and I only lost about 1 MPG. With the 5" straight exhaust this truck sounds mean. The grill guard is a Frontier steel. I am currently working on building a headache rack w/ side rails and will also have 3 lights in each corner. I'm not quite done with it yet but I have a few pics of the building process. I am doing all the fabricating myself. Future plans include powder coating the wheels black and leaving the center caps chrome and also putting a 2" leveling kit on the front end.

The thing is there have been a few generations of 5.9's, and problems specific to them. There was a problem with the lift fuel pump going out, which causes the primary (expensive) fuel pump to eventually die as it has to work too hard. Adding a pressure gauge will let you know the status of the lift pump, and it can be replaced with a quality aftermarket pump.

My greatest fear with getting a used diesel is that a former owner would have chipped the engine, and put alot of strain on the engine and drivetrain. If you can be assured the engine was left stock and recieved normal maintanence, then I'd say its just an issue of finding one for the right price.

Logger,

The problem we have been seeing is the latest 5.9L (610 torque model). The main problem with them we have seen is fuel. These new fuel system on these diesel run at an incredible high pressure (like 30K PSI). This is also the reason why they are a lot quiter than previous diesels, that and a pilot injection they do before primary ignition. Anyways, at that pressure imagine what a piece of dirt does to the tip of the injector. A injector starts to run rich- flooding out a cylinder causing scoring, it can also divert the fuel spray causing hot spots that melt down pistons, or it can just run poorly. The best thing to do if you are looking at a used one is to drive it and see how it runs. Second, there is a blow by tube that runs down by the front differential, check it to see if it is puking oil.
The people having the biggest problem with these engines are people filling their truck up with contaminated fuel from storage tanks or tanks in the back of their truck that are starting to deteriate. We recomend replacing the fuel filter at every oil change to our customers and those that do do not have any problems. It is very easy to do yourself and is cheap insurance compared to an injector(s) or motor.

Hemi

Hemi:

Thanks for the information, it is very useful.

Logger